Acoustic diaphragm



(No Model.)

' W. JONES & W. W. REYNOLDS.

ACOUSTIC DIAPHRAGM.

No. 322,295. Patented July 14,1885.

L1 yen for a N. PETERS. PholoLilhcgnph-r. Wnhingtnn. D.C.

\VILLIAM JONES AND \VARREN -W. REYNOLDS, OF CiiSSOP-OLlS,liil'CillGlrhT.

ACOUSTlC E lAPHRAGhd.

SPECIFICATEON forming part of Letters Patent No. 322,295, dated July 1%,Application filed December 13, 1884. (No model.)

To aZZ whom it may concern:

Be it known that we, WILLIAM J ONES and \VAnnnN W. REYNoLDs, citizens ofthe United States, residing at Oassopolis, in the county of Cass andState of Michigan, have invented a certain new and useful Improvement inAcoustic Diaphragms, which has not been patented to ourselves, nor toothers with our consent or knowledge, in any country, and which has not,according to our knowledge and belief, been in public use or on sale inthe United States for more than two years prior to this application; andwe do hereby declare that the following is a full, clear, and exactdescription of the same, reference being had to the accompanyingdrawing, which represents a diametric section of one of our improveddiaphragms, the thickness being considerably exaggerated for the purposeof showing the more distinctly the several layers of which the diaphragmis composed.

Our invention relates to acoustic diaph ragms of that kind which areused in telephones; and its object more particularly is to provide sucha diaphragm which shall, in conjunction with another similar diaphragmand awire or cord connecting the two, and without the aid of anyelectric or magnetic apparatus, be capable of transmitting theutterances of the human voice or the sound of musical instruments withperfect clearuess to the distance of a mile or more.

To this end it consists in a diaphragm composed of a layer of wood. andone or more layers of paper, preferably with the addition of one or morelayers of canvas or equivalent material, the whole compacted into asingle plate. We will proceed to describe this in detail, and willafterward point out particularly and distinctly what we claim as ourinvention. W'e make the diaphragm of the usual disk form and of two ormore circular layers closely applied the one to the other, so as to formone perfectly-compact disk. For this purpose we apply a cementingsubstance between the layers, preferably either glue or varnish; but anymeans by which the layers can be effectually compacted togethersuch ascompression-wi.ll produce a diaphragm equally eilicient in transmittingsound. The

layer atthe front of the diaphragm nearest to the hearer or speaker, asthe case may be, is of wood, ordinarily a veneer from one ihirtysecondto one-sixteenth of an inch thick, and it is on this layer that weprincipally depend for reproducing the sound vibrations, the lesserthickness being the more sensitive. The wood, however, when used alone,gives out a whizzing sound characterisiic of the material, which,besides being disagreeable, mingles confusingly with the sound whichcomes from the voice of the speaker, and thus makes the reproductionindistinct. We reduce i peculiar whizzing sound to practically noth J byadding to the layer of wood a layer of pa per, )referably paper made ofwood pulp and about equal to the wood in thickness. diaphragm thuscomposed does excellent service as a transmitter of speech; but as it ishardly strong enough to bear for any length of time without detriment.the tension of the connecting-wire, except where the line iscomparatively short, we add, to give i mness to the structure, a sheet(corrcspei g in shape to the other two layers) of canvas or other cloth,whose thickness is not appre ble by ordinary means of measurement. "Weapply it between the wood and the paper. Rawhide, wire-cloth, or anythin and iirm fabric or membrane may be used instead of the canvas.

W'e find in practice that the best results are attained by adding to thestructure, as we have already described it, another layer of canvas orits equivalent and another layer of paper, the latter being also ofabout the same thickness as the wood.

This the preferable form of our improved phragni is the one illustratedin the awing. In this A denotes the button, of wood, metal, or othersuitable material, attached. to the front or outer face of the diaphra mby any convenient means. 13 denotes the wire, hastened at its end to thebutton and passing through diaphragm to a similar diaphragm at the otherend of the line. C denotes the outer or front layer of the diaphragm,being a disk of woe veneer from one-thirty-seooml to oi'ze-si":ccn:n ofan inch thick. D denotes the two layers of paper, each similar in shapeand thickness to the wood; and E denotes the two sheets of canvas orequivalent material interposed, respectively, between the wood and thefirst layer of paper and between the two layers 01' paper. Of course weapply a suitable moutlrpiece to the front of the diaphragm; but as amouthpiece forms no part of the present invention, and is unnecessary toa perfect understanding of it, we have not shown any mouth-piece in thedrawing.

\Vith the diaphragm which we have illustrated we find by actual use thatarticulation is perfectly reproduced, and the tones of each individualvoice are rendered with purity at a distance of seven-eighths of a milefrom the speaker, there being several sharp bends of the wire betweenthe two termini of the line,

and we believe that the apparatus will transniit speech distinctly to amuch greater distance.

brane arranged, respectively,between the wood 0 and the paper andbetween the two layers of paper, and a cementing material, substantiallyas and for the purpose described.

XVILLIAM JONES. UXRBEN \V. REYNOLDS.

Witnesses:

THOMAS H UGGINS, GEORGE H. Rnnrrnrn.

